It is known to modify organic semiconductors with regard to their electrical characteristics, especially their electrical conductivity, by doping them. The doping leads to an increase in the conductivity of charge transport layers, thus reducing ohmic losses, and to an improved passage of the charge carriers within the organic layers.
Aspects of the invention solve the problem of providing p-dopants for doping an organic semiconducting matrix material, especially for manufacturing organic electronic devices, preferably dopants which cause an effective increase in the number of charge carriers in the matrix material.
An organic electronic device according to the disclosure comprises a substrate, a first electrode arranged on the substrate, at least a first functional organic layer arranged on the first electrode and a second electrode arranged on the first functional organic layer. The first functional organic layer of this device comprises a matrix material and a p-dopant with regard to the matrix material; the p-dopant comprises a copper complex containing at least one ligand L of the following formula:
wherein E1 and E2 may be the same or different and represent oxygen, sulfur, selenium or NR′, wherein R represents a substituted or unsubstituted hydrocarbon, which may be branched, linear or cyclic, and wherein R′ represents hydrogen or a substituted or unsubstituted, branched, linear or cyclic hydrocarbon; R′ may also be connected with R.
Thereby, the fact that one layer or one element is arranged or applied “on” or “above” another layer or another element can mean here and hereinafter that one layer or one element is arranged in direct mechanical and/or electrical contact on the other layer or the other element. Furthermore, it can also mean that one layer or one element is arranged indirectly on or respectively above the other layer or the other element. In this case, further layers and/or elements can then be arranged between one and the other layer.
Thereby, the first functional organic layer can particularly be selected from the group comprising one or a plurality of electroluminescent layers (EL), electron blocking layers (EBL), hole transport layers (HTL) and hole injection layers (HIL). Any further functional organic layer can be selected from the group comprising one or a plurality of electron injection layers (EIL), electron transport layers (ETL), hole blocking layers (HBL), electroluminescent layers (EL), electron blocking layers (EBL), hole transport layers (HTL) and/or hole injection layers (HIL). The recombination of electrons and holes leads to the electroluminescence. Individual layers can also have functionalities of a plurality of the aforementioned layers. Thus, a layer can serve, for example, as HIL and as HTL or as EIL and as ETL.
The functional layers can comprise organic polymers, organic oligomers, organic monomers, organic small, non-polymeric molecules (“small molecules”) or combinations thereof.
According to the disclosure it was observed that copper complexes with ligands L being carboxylates, homologues of carboxylates and the respective amides and amidinates may improve the whole transport in a functional organic layer, i.e., the hole-conductivity of the layer is increased by the dopant. If the organic electronic device is a radiation emitting device (for example, an OLED), surprisingly, these dopants usually do not quench radiation emission. Usually, particularly the copper(I) complexes even exhibit luminescence by themselves and can help to detect loss channels in the device fabrication. It was observed for the first time that a radiation emitting compound can also be used to increase hole-conductivity. A further advantage of the present copper complexes is that the starting materials for these complexes are generally of low cost.
The copper complex of the present disclosure serves as a p-dopant; therefore, the copper complex is a metal organic acceptor compound with respect to the matrix material of the first functional organic layer. Normally, the copper complex is a neutral (electron-poor) complex and has at least one organic ligand L, without being restricted to that.
The copper complexes in the first functional organic layer may be isolated molecules. However, usually these copper complexes are connected to molecules comprised in the matrix material by chemical bonds (i.e., the molecules comprised in the matrix material serve as ligands coordinating to the copper complex). Normally, the copper atom (or all of the copper atoms) are coordinated to organic ligands only. However, the organic ligands may possess suitable functional groups which allow linking to form an oligomer or polymer.
In an embodiment the ligand L may be at least bidentate, tridentate or tetradentate, and may particularly contain at least one or two moieties C(=E1)E2 with at least one, two, three, four or more of the donor atoms E1 and E2 of the ligands coordinating to the copper atoms of the present p-dopant. Usually all donor atoms E1 and E2 coordinate to the copper atoms of the present complex. The C(=E1)E2-moiety usually has one negative charge. However, in theory the not deprotonated carboxylic acid (its homologues and the respective amides and amidinates) can also serve as a ligand. In general, the ligand L of the present disclosure contributes negative charges to the complex (i.e., one negative charge per CE2 group).
According to an embodiment, the copper complex of the present disclosure is (in the state where no matrix molecule coordinates to the copper atom) a homoleptic complex where only ligands L are coordinated to the central copper atom. Further, the copper complex (particularly the copper complex containing only ligands L) is often, as long as no molecule of the matrix material coordinates to the central copper atom, complex with square planar or linear molecular geometry, particularly if copper-copper interactions are disregarded. Upon coordination of a matrix molecule the geometry is usually altered and, for example, a pentagonal-bipyramidal coordination geometry or a square pyramidal molecular geometry results. Usually, in all alternatives described in this paragraph the copper complex is still, as mentioned before, a neutral complex.
It shall be understood that previous definitions of the copper complexes and/or ligands apply to mononuclear copper complexes but also to polynuclear copper complexes. In polynuclear copper complexes the ligand L may bind to only one copper atom and also to two copper atoms (i.e., bridging two copper atoms). If ligands L are contained which are tridentate, tetradentate or multidentate ligands, also more than two copper atoms of the polynuclear copper complex may be bridged. In the case of polynuclear copper complexes copper-copper bonds may exist between two or more copper atoms. However, particularly as far as copper (I) complexes are concerned, usually no copper-copper bonds (of the copper complexes without coordinating molecules of the matrix) are observed. This may be proven by x-ray spectroscopy and by absorption spectroscopy (which shows a square planar surrounding of the copper atoms, i.e., a copper atom surrounded by four organic ligands, particularly four ligands L or copper complexes with two coordinated ligands, particularly two ligands L, with a linear geometry of the complex). Copper(I) complexes often show cuprophilic Cu—Cu interactions; The Cu—Cu carboxylate bridged distances may very broadly vary from 2.5 to 3.2 Å.
If polynuclear copper complexes are used, the organic electronic device and in particular the first functional organic layer exhibits an improved lifetime. Presumably, charges transported via the first functional organic layer may cause a destabilizing effect with regard to the copper complex. If, however, more than one copper atom is present in the copper complex, the destabilizing effect is distributed on all copper-atoms. Therefore, polynuclear complexes usually show an improved stability compared to mononuclear complexes.
In an embodiment, the polynuclear copper complexes show a so-called “paddle-wheel” structure, particularly as far as copper (II) complexes are concerned. A paddle-wheel complex is a complex with usually two metal atoms, in the present case copper atoms, which are bridged by one, two, three, four or even more multidentate ligands, in the present case usually two or most often four ligands L. Usually the coordination mode of all ligands (with respect to the copper atoms) is almost identical so that, with respect to copper atoms and ligands L, at least one two-fold or four-fold rotation axis through two of the copper atoms contained in the polynuclear complex is defined. Square planar complexes often exhibit an at least four-fold rotation axis; linear coordinated complexes often show a two-fold rotation axis.
In an embodiment of the present application, the copper atom of the mononuclear complex or at least a part of the copper atoms (usually all copper atoms) of the polynuclear copper complex shows the oxidation state +2. In these complexes the ligands are mostly coordinated in a square planar geometry (in the state where no molecules of the matrix are coordinating to the copper atom).
In a further embodiment the copper atom in the mononuclear complex or at least a part of the copper atoms (usually all copper atoms) of the polynuclear complex are in the oxidation state +1. In those complexes the coordination mode of the copper atom is mostly linear (as long as no molecule of the matrix coordinates to the copper atom).
Complexes containing copper (II) atoms usually exhibit a better hole transport ability than complexes containing copper (I) atoms. Copper (I) complexes have a closed shell d10 configuration. Therefore, the effect originates primarily form the Lewis acidity of the copper atom. Copper (II) complexes have a not closed d9 configuration, thus giving rise to an oxidation behavior. Partial oxidation increases the hole density. On the other hand, complexes containing copper (I) atoms are often thermally more stable than corresponding copper (II) complexes.
In a preferred embodiment, the copper complex of the present disclosure (in the state where no molecules of the matrix are coordinated) is Lewis-acidic. A Lewis-acidic compound is a compound which acts as an electron pair acceptor. A Lewis-base, therefore, is an electron pair donator. The Lewis-acidic behavior of the present copper complexes is particularly related to the molecules of the matrix material. Therefore, the molecules of the matrix material usually act as a Lewis-base with respect to the Lewis-acidic copper complexes.
A Lewis-acidic complex according to the present disclosure may also be a complex as described before wherein a solvent molecule coordinates to the central copper atom at the free coordination site described before. However, particularly the tested copper complexes described in the examples below do not comprise a solvent molecule.
In the present disclosure the copper atom contains an open (i.e., a further) coordination site. To this coordination sites the coordination of a (Lewis-basic) compound, particularly an aromatic ring or a nitrogen atom of an amine component contained in the matrix material can coordinate (see the following schemes 1 and 2):


However, also other groups different from aromatic rings or amine nitrogen atoms are possible as far as aromatic ring systems are contained also hetero aromatic rings may coordinate to the copper atom. Often, a coordination of the nitrogen atom of an amine component is observed.
In an embodiment of the present disclosure, the ligand L coordinating to the copper atom contains a group R representing a substituted or unsubstituted hydrocarbon, which may be branched, linear or cyclic. The branched, linear or cyclic hydrocarbon may particularly contain 1-20 carbon atoms, for example, methyl, ethyl or condensed substituents (like decahydronaphthyl or adamantyl, cyclo-hexyl or fully or partly substituted alkyl-moieties). The substituted or unsubstituted aromatic groups R may, for example, be phenyl, biphenyl, naphthyl, phenanthryl, benzyl or a hetero aromatic residue, for example, a substituted or unsubstituted residue selected from the heterocycles depicted in the following:

In a further embodiment of the present disclosure, the ligand L coordinating to the copper atom contains a group R representing an alkyl and/or aryl group wherein the alkyl, aryl or aralkyl group bears at least one electron withdrawing substituent. The copper complex may contain more than one type of carboxylic acids (mixed systems), amides and amidinates, wherein the word “type” refers on the one hand to the substituent R and on the other hand to the hetero atoms being connected to the copper.
An electron withdrawing substituent according to this disclosure is a substituent which reduces the electron density at the atom to which the electron withdrawing substituent is bound compared to the respective atom bearing a hydrogen atom instead of the electron withdrawing substituent.
The electron withdrawing groups may, for example, be selected from the group containing halogens (e.g., chlorine and particularly fluorine), nitro groups, cyano groups and mixtures of these groups. The alkyl and/or aryl group may bear exclusively electron withdrawing substituents, for example, the aforesaid electron withdrawing groups or hydrogen atoms as well as one or more electron withdrawing substituents.
If ligands L wherein the alkyl and/or aryl groups bear at least one electron withdrawing substituent are used, the electron density at the central atom (s) of the copper complex can be reduced; therefore, the Lewis-acidity of the copper complex can be increased.
The ligand L may, for example, be the anion of the following carbonic acids: CHalxH3-xCOOH, particularly CFxH3-xCOOH and CClxH3-xCOOH, (wherein x represents an integer from 0 to 3 and Hal represents an halogen atom), CR″yHalxH3-x-yCOOH (wherein x and y are integers and x+y=a number from 1 to 3 and wherein y is at least 1 and Hal represents a halogen atom); the substituent R″ may be alkyl or hydrogen or an aromatic group, particularly phenyl; all groups described before for the residue R″ may contain electron withdrawing substituents, particularly the electron withdrawing substituents mentioned before or a derivative of benzoic acid containing an electron withdrawing substituent (for example, ortho-, para- or meta-fluoro benzoic acid, ortho-, para- or meta-cyano benzoic acid, ortho-, para- or meta-nitro benzoic acid or benzoic acids bearing one or more fluorinated or perfluorinated alkyl groups, for example, a tri-fluoro methyl group. For example, the ligand L may be the anion of the following carbonic acid R″—(CF2)n—CO2H with n=1-20; R″ stands for the same groups as listed above for R, particularly again a group bearing electron withdrawing moieties (for example, fully or partially fluorinated aromatic compounds). If the volatility of the ligand L is too high (which may occur, for example, if perflorinated acetates and propionates are used), the molecular weight and thus the evaporation temperature can be increased, without losing too much Lewis acidity with respect to the trifluoroacetate. Therefore, for example, fluorinated, particularly perfluorinated, homo- and heteroaromatic compounds can be used as moieties R and R″, respectively. Examples are the anions of fluorinated benzoic acids:
wherein the phenyl ring bears 1 to 5 fluorine substiutents (i.e., x=1-5). Particularly the following substituents, which are strong Lewis acids, (or the corresponding substituents bearing chlorine atoms instead of fluorine atoms) may be bound to the carboxylate group:

Furthermore, the anions of the following acid may be used as ligands:
wherein X may be a nitrogen atom or a carbon atom bearing, for example, a hydrogen atom or a fluorine atom. According to an embodiment three Atoms X stand for N and two for C—F or C—H (triazine derivatives). Also the anions of the following acid may be used as ligands:
wherein the naphthyl ring bears 1 to 7 fluorine substiutents (i.e., y=0-4 and x=0-3 wherein y+x=1-7).
According to an embodiment, ligands L having the following structure may be used:
wherein E1 and E2 are defined as above, wherein Y1, Y2, Y3, Y4 and Y5 represent the same or different groups or atoms and wherein Y1, Y2, Y3, Y4 and Y5 are independently selected from the following atoms and/or groups: C—F, C—Cl, C—Br, C—NO2, C—CN, N, C—N3, C—OCN, C—NCO, C—CNO, C—SCN, C—NCS, and C—SeCN, particularly independently selected from the following atoms and/or groups C—F, C—NO2, C—CN, and N. Thus, all ring members beside the C-Atom connected to the CE2− group are selected from these atoms and/or groups. These ligands L may for example be selected from the following ligands:

According to this embodiment also aromatic substituents R being different from substituents R deriving from six-membered rings, i.e., from phenyl are possible, for example, substituents R deriving from polycyclic aromats, for example, deriving from 1-nayphthyl and 2-naphthyl. These ligands L may, for example, be selected from the following ligands:

In particular, fluorine as electron withdrawing substituent is mentioned as copper complexes containing fluorine atoms in the coordinated ligands may be evaporated and deposited more easily. A further group to be mentioned is the trifluoromethyl group.
In a further embodiment of the present disclosure, the group R′ (in the case of amidinates one or both of the groups R′) is represented by a substituted or unsubstituted, branched, linear or cyclic hydrocarbon which bears at least one electron withdrawing substituent. This electron withdrawing substituent is defined as above with respect to the group R.
In an embodiment, the first functional layer is a hole-transport layer. The addition of the copper complex to the matrix material of the hole-transport layer results in an improved hole-transport compared to the matrix material containing no p-dopant. This improved hole-transport may be explained by the transfer of the hole (or a positive charge) from the molecules of the matrix material being coordinated to the copper complex to the copper atoms and vice versa. This transfer is depicted in the following scheme 3 containing several mesomeric structures of a copper (II) complex (the ligands L or any other ligands or additional copper atoms contained in the copper complex being omitted for the purpose of clarity).

If the device according to the present disclosure is a radiation emitting device, usually no exciton blocking layers between the light emitting layer and the hole-transport layer acting as a first functional organic layer are necessary as no quenching occurs upon addition of the p-dopant to the hole-transport layer.
The matrix material of the hole-transport layer may be selected from one or more compounds of the following group consisting of NPB (N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-benzidine, β-NPB (N,N′-bis(naphthalen-2-yl)-N,N-bis(phenyl)-benzidine), TPD (N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-benzidine), N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-2,2-dimethylbenzidine, Spiro-TPD (N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-9,9-spirobifluorene), Spiro-NPB (N,N′-bis(naphthalen-1-yl)-N,N-bis(phenyl)-9,9-spirobifluorene), DMFL-TPD (N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-9,9-dimethylfluorene, DMFL-NPB (N,N′-bis(naphthalen-1-yl)-N,N′-bis(phenyl)-9,9-dimethylfluorene), DPFL-TPD (N,N′-bis(3-methylphenyl)-N,N′-bis(phenyl)-9,9-diphenylfluorene), DPFL-NPB (N,N′-bis(naphth-1-yl)-N,N′-bis(phenyl)-9,9-diphenylfluorene), Sp-TAD (2,2′,7,7′-tetrakis(m,n-diphenylamino)-9,9′-spirobifluorene), TAPC (di-[4-(N,N-ditolyl-amino)-phenyl]cyclohexane), Spiro-TTB (2,2′,7,7′-tetra(N,N-di-tolyl)amino-spiro-bifluorene), BPAPF (9,9-bis[4-(N,N-bis-biphenyl-4-yl-amino)phenyl]-9H-fluorene), Spiro-2NPB (2,2′,7,7′-tetrakis[N-naphthyl(phenyl)-amino]-9,9-spirobifluorene), Spiro-5 (2,7-bis[N,N-bis(9,9-spiro-bifluoren-2-yl)-amino]-9,9-spirobifluorene), 2,2′-Spiro-DBP (2,2′-bis[N,N-bis(biphenyl-4-yl)amino]-9,9-spirobifluorene), PAPB (N,N′-bis(phenanthren-9-yl)-N,N′-bis(phenyl)-benzidine), TNB (N,N,N′,N′-tetra-naphthalen-2-yl-benzidine), Spiro-BPA (2,2′-bis(N,N-di-phenyl-amino)-9,9-spirobifluorene), NPAPF (9,9-Bis[4-(N,N-bis-naphth-2-yl-amino)phenyl]-9H-fluorene), NPBAPF (9,9-bis[4-(N,N′-bis-naphth-2-yl-N,N′-bis-phenyl-amino)-phenyl]-9H-fluorene), TiOPC (titanium oxide phthalocyanine), CuPC (copper phthalocyanine), F4-TCNQ (2,3,5,6-tetrafluor-7,7,8,8,-tetracyano-quinodimethane), m-MTDATA (4,4′,4″-tris(N-3-methylphenyl-N-phenyl-amino)triphenylamine), 2T-NATA (4,4′,4″-tris(N-(naphthalen-2-yl)-N-phenyl-amino)triphenylamine), 1T-NATA (4,4′,4″-tris(N-(naphthalen-1-yl)-N-phenyl-amino)triphenylamine), NATA (4,4′,4″-tris(N,N-diphenyl-amino)triphenylamine), PPDN (pyrazino[2,3-f][1,10]phenanthroline-2,3-dicarbonitrile), MeO-TPD (N,N,N′,N′-tetrakis(4-methoxyphenyl)benzidine), MeO-Spiro-TPD (2,7-bis[N,N-bis(4-methoxy-phenyl)amino]-9,9-spirobifluorene), 2,2′-MeO-Spiro-TPD (2,2′-bis[N,N-bis(4-methoxy-phenyl)amino]-9,9-spirobifluorene), β-NPP(N,N′-di(naphthalen-2-yl)-N,N′-diphenylbenzene-1,4-diamine), NTNPB (N,N′-di-phenyl-N,N′-di-[4-(N,N-di-tolyl-amino)phenyl]benzidine) and NPNPB (N,N′-di-phenyl-N,N′-di-[4-(N,N-di-phenyl-amino)phenyl]benzidine).
In a further embodiment, the first functional layer of the organic electronic device of the present application may be an electron blocking layer. If the copper complexes according to the present disclosure were used in an electron blocking layer, even if matrix materials usually used for electron transport materials are contained, almost no electron conductivity was observed. As mentioned before, every matrix material used in electronic organic devices may be the matrix material of the first functional layer being an electron blocking layer, even electron transporting matrix materials. For example, the matrix material can be a matrix material usually used for electron blocking layers. The (electron conducting) matrix material can, for example, be selected from one or more of the materials of the group consisting of Liq (8-hydroxyquinolinolato-lithium), TPBi (2,2′,2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole)), PBD (2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole), BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline), BPhen (4,7-Diphenyl-1,10-phenanthroline), BAlq (bis-(2-methyl-8-quinolinolate)-4-(phenylphenolato)aluminum), TAZ (3-(4-biphenylyl)-4-phenyl-5-tert-butylphenyl-1,2,4-triazole), CzSi (3,6-bis(triphenylsilyle)carbazole), NTAZ (4-(naphthalen-1-yl)-3,5-diphenyl-4H-1,2,4-triazole), Bpy-OXD (1,3-bis[2-(2,2′-bipyridine-6-yl)-1,3,4-oxadiazo-5-yl]benzene), BP-OXD-Bpy (6,6′-bis[5-(biphenyl-4-yl)-1,3,4-oxadiazo-2-yl]-2,2′-bipyridyl), PADN (2-phenyl-9,10-di(naphthalen-2-yl)-anthracene), Bpy-FOXD (2,7-bis[2-(2,2′-bipyridine-6-yl)-1,3,4-oxadiazo-5-yl]-9,9-dimethylfluorene), OXD-7 (1,3-bis[2-(4-tert-butylphenyl)-1,3,4-oxadiazo-5-yl]benzene), HNBphen (2-(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline), NBphen (2,9-bis(naphthalen-2-yl)-4,7-diphenyl-1,10-phenanthroline), 3TPYMB (tris(2,4,6-trimethyl-3-(pyridin-3-yl)phenyl)borane) and 2-NPIP (1-methyl-2-(4-(naphthalen-2-yl)phenyl)-1H-imidazo[4,5-f][1,10]phenanthroline).
In a further embodiment, the first functional layer is an emission layer. Therefore, the first functional layer comprises a matrix material, the copper complex according to the disclosure and a light emitting material; alternatively, the first functional organic layer may comprise a light emitting matrix material and the copper complex. In theory, the first functional organic layer according to this embodiment may also contain a matrix material and the p-dopant (copper complex), wherein the p-dopant additionally serves as a light emitting substance. However, usually the intensity of the light emitted by the copper complexes according to the disclosure exhibits, with respect to the light emitting materials used for OLEDs known by the skilled person, are a relatively low intensity. Therefore, applications using the copper-complexes/p-dopants according to the disclosure as light emitting molecules will usually contain a further emitter layer and the emitter layer containing the copper complex will only serve for changing the spectrum (or the color) of the emitted radiation.
As already outlined before, the matrix material of the first functional organic layer comprises an organic compound or consists of this organic compound. Usually, at least a part of this organic compound coordinates to the copper complex (i.e., the p-dopant according to the disclosure). Therefore, not all molecules of the organic material of the matrix material coordinate to copper atoms. However, one and the same organic compound may also coordinate to two or sometimes even more copper atoms. If the organic compound contained in the matrix material of the first functional organic layer contains, as described before, two or more coordination sites a part of which coordinates two copper atoms catenarian structures or netlike structures of a plurality of the copper complexes (as defined in claim 1) and a plurality of organic molecules may be formed.
The coordination of the organic compound may result from interactions of σ-electrons and/or π-electrons of the organic compound with the copper atom. Usually the hole-transport ability is improved if the number of catenarian or netlike structures in the first functional layer is increased. Therefore, also the increase of possible coordination sites usually leads to an increase of hole-transport as the formation of netlike structures or catenarian structures is favored.
Furthermore, also the structure of the copper complex has an influence on the propensity of coordination of the organic compound. The smaller the substituents R of the ligand L are, the less shielded the free coordination site of the copper atom is and the easier a coordination site of the organic compound will coordinate to the copper atom. Therefore, substituents R being linear alkyl groups may be used, if a “deshielding” of the copper atom is desired.
In an embodiment, the amount of p-dopant/copper complex contained in the first organic functional layer is 50% by volume with respect to the matrix material, for example, the amount of the p-dopant may be 30% by volume or less. Often the amount of the p-dopant with respect to the matrix material will be at least 5% by volume and 15% by volume at the most. The concentration by volume can easily be observed by comparison of evaporated matrix material and evaporated p-dopant if the first functional organic layer is produced by simultaneous evaporation of matrix and p-dopant (the layer thickness for and after evaporation can be measured). A variation of the amount of p-dopant can easily be realized by changing the temperature used for evaporation of the source of p-dopant and matrix material. In embodiments where no evaporation of the matrix material and the p-dopant is used, the respective proportion of p-dopant in weight percent (calculated by multiplication with the density of the respective material) can easily be calculated.
The organic electronic device according to the disclosure may, in particular, be a radiation emitting device, for example, an organic light emitting diode (OLED). The organic electronic device may further be, for example, an organic field effect transistor, an organic solar cell, a photo detector, a display or in general also an opto-electronic component. An organic electronic device containing the p-dopants/copper complexes according to the disclosure serving as components improving hole-transport is particularly suited for organic electronic devices wherein the efficiency strongly depends on a good hole-transport. For example, in an OLED, the generated luminescence is directly dependent on the number of formed excitons. The number of excitons is directly dependent on the number of recombining holes and electrons. A good hole-transport (as well as electron transport) gives rise to a high rate of recombination and, therefore, to a high efficiency and luminescence of the OLED. Furthermore, the power efficiency increases, when a voltage drop over the transport layers decreases. If the conductivity of the transport layers is about 3 to 4 orders of magnitude higher compared to the other layers in the stack, the voltage drop over the transport layers will usually no longer be observable. The most “power” efficient device will usually be a device, where the voltage is dropped almost only along the emitting layers.
In an embodiment of the present disclosure, the first functional organic layer of the organic electronic device is obtainable (or obtained) by simultaneous evaporation of the copper complex (p-dopant) and the matrix material. The simultaneous evaporation of the copper complex and the matrix material enables an interaction of those molecules.
In an embodiment, the organic electronic device according to the present disclosure can be produced by the following method:
A) providing a substrate,
B) arranging a first electrode on the substrate,
C) arranging at least the first functional organic layer on the first electrode,
D) arranging a second electrode on the at least first functional organic layer.
Preferably, the first functional organic layer is produced by simultaneous evaporation of the copper complex according to the present disclosure and the organic compound of the matrix material. Upon evaporation of the copper complex, often dimeric species are observed in the vapor phase. Therefore, complexes with the same type of ligands and the same ligand/copper atom ratio show the same evaporation temperature.
In an embodiment, the electrodes arranged in step B), step D) or in both steps are patterned.
The present disclosure also provides a semiconducting material produced using a copper complex (p-dopant) as described before. Usually this semiconducting material is obtainable by combining a matrix material and the aforesaid copper complex, particularly, by simultaneous evaporation of the matrix material and the copper complex.
Further, the objective of the present disclosure is achieved by a dopant for doping an organic semiconducting matrix material comprising at least two copper atoms, and at least one ligand L bridging the two copper atoms, wherein the ligand L is represented by the following formula:
wherein E1 and E2 and R have the meaning as described before. In particular, this polynuclear copper complex is a Lewis-acidic copper complex. According to an embodiment R does not in all coordinated ligands L represent CF3. According to a further embodiment R in none of the ligands L represents CF3.
In a further embodiment the copper complex comprises four, particularly in a “four-membered” ring, or six copper atoms, particularly in a “six-membered” ring, or polymeric species comprising a plurality of copper atoms in a chain-like structure.
In a further embodiment, the polynuclear copper complex contains at least one ligand L (and is, for example, a homoleptic complex) wherein the substituent R of the ligand L contains at least two carbon atoms.
In a further embodiment the copper complex contains a mixed ligand system, for example, a mixture of aliphatic ligands (like trifluoroacetate) and aromatic ligands (like perfluorobenzoate). These mixed systems may, for example, be obtained by partial substitution of the ligands of a homoleptic complex (for example, a homoleptic trifluoroacetate complex).